GitHub Actions FTW?

Converting the build and deploy process to use github actions. Let's see if it worked.

Followed these docs:

• https://docs.github.com/en/pages/getting-started-with-github-pages/configuring-a-publishing-source-for-your-github-pages-site#publishing-with-a-custom-github-actions-workflow

Let's see how this goes.

Follow-up

It worked great!

Added the two wokflow files in this commit.

I discovered that I needed to commit a yarn.lock file in order for the workflow to succeed. Previously I had been using npm to build and test, but the supplied workflow uses yarn.